​
Syntax

create_function ::= CREATE [ OR REPLACE ] FUNCTION function_name 
                    ( [ parameter_list ] )
                    RETURNS return_type
                    LANGUAGE language_name
                    [ SECURITY { DEFINER | INVOKER } ]
                    [ volatility ]
                    [ STRICT ]
                    AS function_body

function_name ::= [schema.]name

parameter_list ::= parameter [, ...]

parameter ::= [ parameter_mode ] [ parameter_name ] parameter_type [ DEFAULT default_value ]

parameter_mode ::= IN | OUT | INOUT

argument_list ::= data_type [, ...]

return_type ::= data_type
              | SETOF data_type
              | TABLE ( column_name data_type [, ...] )
              | trigger

language_name ::= plpgsql | sql | c | internal

volatility ::= IMMUTABLE | STABLE | VOLATILE

function_body ::= 'definition'
                | $$definition$$
                | $tag$definition$tag$
pgschema understands the following CREATE FUNCTION features:
  • Schema-qualified names: Functions can be defined in specific schemas
  • Parameters:
    • IN, OUT, INOUT parameter modes
    • Default parameter values
    • Named parameters with data types
  • Return types:
    • Scalar data types
    • SETOF for set-returning functions
    • TABLE for table-returning functions
    • trigger for trigger functions
  • Languages: Any PostgreSQL procedural language (plpgsql, sql, c, internal, etc.)
  • Security: DEFINER or INVOKER
  • Volatility: IMMUTABLE, STABLE, or VOLATILE
  • STRICT: Returns NULL automatically if any argument is NULL
  • Function body: Any valid function definition with proper dollar-quoting

​
Canonical Format

When generating migration SQL, pgschema produces functions in the following canonical format: 
CREATE OR REPLACE FUNCTION [schema.]function_name(
    parameter_name parameter_type[ DEFAULT default_value][,
    ...]
)
RETURNS return_type
LANGUAGE language_name
SECURITY { DEFINER | INVOKER }
[ IMMUTABLE | STABLE | VOLATILE ]
[ STRICT ]
AS $tag$function_body$tag$;
Key characteristics of the canonical format:
  • Always uses CREATE OR REPLACE FUNCTION for modifications
  • Parameters are formatted with line breaks for readability
  • Explicitly specifies SECURITY mode (INVOKER is default if not specified)
  • Includes volatility when specified
  • Includes STRICT when the function should return NULL on NULL input
  • Uses intelligent dollar-quoting with automatic tag generation to avoid conflicts with function body content
  • For DROP operations: DROP FUNCTION IF EXISTS function_name(argument_types);